Phragmites australis • Class B

Phragmites or common reed is a very large, perennial grass that grows up to 15 feet tall. It has large hollow stems, which produce leaves up to 16 inches long along most of their length. The short papery bracts, called ligules, grow from the leaf where it bends out from the stem and are yellow or greenish in color. It produces dense feathery flower heads 8 to 16 inches long. 

The non-native genotype of Phragmites australis will colonize and displace the other plants in a wetland community, often forming dense monocultures. It displaces wildlife because it alters the wetland environment so dramatically. Water quality is also deteriorated by the presence of this plant, because water flow or circulation is adversely affected by this species. 

Seedlings may be produced on nearly any site that has some surface water, even brackish or salt water. It is typically found in or near wetlands. 

Below the water line, the plant’s root system secretes an acid so toxic that it causes the protein structure in nearby plant roots to rots away, killing off all neighboring plant life, not just defensively, but offensively so that it can spread to new areas. 

Common Reed reproduces both by large quantities of wind and water dispersed seed and by rhizomes. Once a stand is established it spreads primarily through vegetative means. 

Cutting has been used successfully for control. Since it is a grass, cutting several times during a season, at the wrong times, may increase stand density. However, if cut just before the end of July most of the food reserves produced that season are removed which reduces the plant's strength. This process must be repeated for several years to be effective. Care must be taken to remove cut shoots to prevent regrowth. 

• Care must be taken not to produce new plants when clearing common reed infestations. The entire plant material should be removed to prevent rhizomes from producing new plants.

• There are no known biological control agents for Common Reed. 

• Since Common Reed is found in wetland areas, the use of an herbicide formulated for aquatic settings is required. Please note that aquatic herbicides are restricted for use in Washington State to licensed applicators only. 

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